Decolorization of azo dyes by a novel aerobic bacterial strain Bacillus cereus strain ROC

Abstract

Synthetic dyes are widely used as colorant compounds in various industries for different purposes. Among all the dyestuffs, azo dyes constitute the largest and the most used class of dyes. These dyes and their intermediate products are common contaminants of ground water and soil in developing countries. Biological methods have been found to be promising for the treatment and degradation of these compounds. In the present study, we focused on the biological removal of azo dyes (Reactive orange 16 and Reactive black 5) under aerobic conditions using an indigenous bacterial strain isolated from contaminated industrial areas. The bacterial isolate was identified as Bacillus cereus strain ROC. Degradation experiments under agitation with both free and immobilized cells indicates that this strain degrades both azo- dyes in 5 days. The immobilized cells were more proficient than their free cell counterparts. The toxicity of the biotransformation products formed after decolorization were assessed by conducting bacteriotoxic and phytotoxic assays. All the toxicity assays indicate that the dyes’ degraded products were non-toxic in nature, as compared to the dyes themselves. The kinetics of the azo dyes’ degradation was also studied at various initial concentration ranges from 50 mg/L to 250 mg/L by growth independent kinetic models. Zero-order kinetics were fit to the experimental data, producing values of least squares regression (R2) greater than 0.98, which indicates that the bacterial strain degrades both dyes by co-metabolism rather than utilizing them as sole energy source. These results indicate that the Bacillus cereus ROC strain has great potential to degrade dye-contaminated water and soil.

Decolorization of reactive dyes by the white rot fungus Phanerochaete velutina in presence of Zn and ZnO nanoparticles

“…In particular, most of the studies were carried out in bioreactors and used stirring to distribute the cells and the dye well. For example, Fareed et al shows that temperature can have a strong influence on the degradation efficiency of Bacillus cereus on reactive dyes (Fareed et al 2022). They showed that the decolorization efficiency was at 100% at 37 °C compared to 40% at 30 °C for 100 mg l −1 of RO-16.…”

Bioremediation of Textile Azo Dyes Amido Black 10B, Reactive Black 5, Reactive Blue 160 by <i>Lentinus squarrosulus</i> AF5 and Assessment of Toxicity of the Degraded Metabolites

“…All the group of samples were subjected for incubation in triplicates in similar environmental setups. After seven days, the germination rate and the size of the shoot and root were measured [22] [23] [24] [25] [26].…”

Recent Strategies for the Remediation of Textile Dyes from Wastewater: A Systematic Review

“…In one investigation, Louati et al [102], found 100% decolorization of dyes at pH 8 by using Pseudomonas aeruginosa strain Gb30, whereas Montanez-Barragan et al [103] observed above 90% decolorization of dyes at pH 6-11 with Halomonas species. Another researcher, Shi et al [104], found 100% dye removal of Brilliant Crocein by using the bacteria Providencia rettgeri, while Fareed et al [105] found 80-100% decolorization of dyes by using free and immobilized cells of Bacillus cereus at temperatures of 32 [107] observed the complete decolorization of malachite green and crystal violet at pH 3-10 and a temperature of 20-45 • C after 12 h of incubation under optimal environmental conditions using Serratia species, which is a new bacterial strain identified via 16S rDNA analysis. In a recent study, Tripathi et al [10] observed 98% dye decolorization of crystal violet dye using a native multiple metal-tolerant Aeromonas caviae MT-1 isolate.…”